1. Field of the Invention
The present invention is directed to a modular ramp system which can be assembled with a threshold in order to facilitate passage of, inter alia, wheeled vehicles including wheelchairs through doorways and other entrance ways.
2. Description of the Related Art
Ramps which can be fitted to thresholds in order to facilitate travel by wheelchairs and other wheeled vehicles over the threshold are already known in the art. Examples of such structures are shown in FIGS. 18-20.
FIG. 18 shows a metal component, or member, 20 constructed to form part of a ramp that can facilitate passage over a step 11 which may be located at a doorway or may simply be a change in elevation of a floor or walkway. Such a step may, as indicated in FIG. 18, have a height of a 1/2". These steps can have other heights and are often referred to in the art as an "offset", which term will be employed hereinafter. Component 20 presents an upper surface having a horizontal portion 21, a relatively long sloping ramp portion 22 and a relatively short sloping ramp portion 23.
An additional ramp component can be placed adjacent ramp portion 22 to provide a ramp surface which extends to the level of the floor or walkway.
This additional component may be a preformed concrete ramp component or a metal ramp component such as the component, or member, 25 shown in FIG. 19.
As shown in FIG. 19, component 25 may be used alone as a ramp whose high end abuts offset 11. In FIG. 20, components 20 and 25 are placed together to abut one another and firm the complete ramp described above.
Reverting to FIG. 18, ramp portion 23 can be somewhat steeper than ramp portion 22 because of its smaller total length.
One of the major problems associated with modular threshold ramps is that the respective ramp members tend to slide apart and create a safety hazard. The prior art attempts to solve this problem by welding the ramp members together during installation. For example, abutting vertical legs of components 20 and 25 of FIG. 20 could be welded together. Welding, however, adds significant time and expense to the installation process. Additionally, if one of the ramp members is damaged, the weld must be broken in order to replace the damaged member. Breaking the weld may cause damage to the other ramp member, thus necessitating the replacement of the previously undamaged portion of the ramp. Accordingly, welding adds significant time and expense to the removal and replacement of damaged portions of the modular ramp.
Another problem often encountered results from the fact that there are a number of standard threshold offset heights and that when threshold ramps are first installed and/or retrofitted, there are often numerous limitations placed on particular ramp dimensions. For example, under the Americans with Disabilities Act of 1990 Accessibility Guidelines (ADAAG), the slope of threshold ramps must be 1:12 for new buildings and can be retrofitted to a maximum of 1:8 in some existing buildings. Accordingly, the dimensions of prefabricated threshold ramps must be individualized for each standard offset height in order to meet the threshold ramp slope requirements. Moreover, prior to retrofit of an existing building, the height of all of the threshold offsets in the building must be measured so that the proper number of each size of prefabricated ramp can be ordered. Thus, the necessity of using prefabricated ramps adds significant time and expense to the retrofit process.
A similar problem relates to the fact that not all threshold offsets are one of the standard heights (1/2", 3/4", etc). Prefabricated threshold ramps are useless in such situations and a custom threshold ramp must be produced at great expense.